Police in Moscow have detained Pavel Shekhtman, a Russian civil rights activist and Kremlin critic.
Shekhtman's lawyer told the online news site kasparov.ru that his client was detained on October 8 over recent publications in the Internet, but did not give details.
He said Shekhtman was being held in a Moscow pretrial detention center.
Shekhtman is known for his criticism of the Kremlin over rights abuses in Russia.
In March, Shekhtman was attacked by members of a group led by nationalist opposition politician Eduard Limonov over his criticism of Russia's actions in Ukraine.
Russia annexed the Crimea region form Ukraine in March and Kyiv and the West say Moscow has sent troops and weapons to help pro-Russian separatists in eastern Ukraine.